Image forming apparatus and document reading device

ABSTRACT

In accordance with the present invention, in an image forming apparatus, two document reading sections, a document conveying unit and a fixing unit are efficiently laid out so as to occupy a minimum of space available in the apparatus. Also, the document reading device is capable of reading even a relatively thick or a relatively long document conveyed by a turn-over type sheet-through document conveying device and not feasible for a turn-over path.

This application is a Divisional of application Ser. No. 08/834,873filed Apr. 10, 1997, now U.S. Pat. No. 5,986,775.

BACKGROUND OF THE INVENTION

The present invention relates to a facsimile apparatus, copier orsimilar image forming apparatus including a reading section for readinga document in the form of a sheet with stationary optics while conveyingthe document. Also, the present invention relates to a document readingdevice applicable to, e.g., a facsimile apparatus or a copier forreading a document or sheet with stationary optics while conveying thedocument.

An image forming apparatus having an apparatus body and one or moresystem units connected thereto is conventional. The system units arecommonly connectable to different types of image forming apparatuses andthere by promote cost saving. It is therefore preferable with an imageforming apparatus to simplify the functions of the apparatus body, sothat sections which can be separated from the apparatus body can beimplemented as system units.

It is a common practice with a facsimile apparatus or similar imageforming apparatus including a reading section to mount an ADF (AutomaticDocument Feeder) in order to promote the efficient handling of a stackof documents. Basically, the ADF feeds one document from its tray orstacking section to a transport path while separating it from theunderlying documents. The transport path extends linearly from thedocument feed side to a document discharge side. A contact line imagesensor or similar stationary optics is located at a preselected positionon the transport path, and reads the document being conveyed along thetransport path. A relatively thick document not feasible for the aboveseparation and feed mechanism is directly inserted to the readingsection by hand, and then automatically conveyed. The linear transportpath, however, has a substantial length and renders the entire apparatusbulky. To save space, there has been proposed and put to practical use aturn-over type sheet-through ADF capable of discharging a document readby stationary optics in the direction of sheet feed, as taught inJapanese Patent Publication No. 63-40514 by way of example. This kind ofADF has a document separating and feeding section for feeding onedocument while separating it from the others, a generally U-shapedturn-over path, and a transport path having a reading position assignedto stationary reading optics and for conveying the document turned overby the turn-over path.

Assume that an image forming apparatus has its document reading section,document conveying section along which a document fed from a stackingsection is conveyed, and fixing unit for fixing a toner image on a sheetconstructed into independent units, and that such units are individuallyconnectable to the apparatus body. This brings about a drawback that thespace available in the apparatus body cannot be efficiently used by theunits, increasing the overall size of the apparatus body. Particularly,to read both sides of a document while conveying it only once, thedocument conveying unit must turn over the document and again feed it tothe reading position, or two reading sections must be located at bothsides of the transport path. This kind of arrangement increases thespace to be allocated to the conveying unit or the spaces to beallocated to the reading units, making it difficult to miniaturize theapparatus.

The conventional turn-over type sheet-through ADF has the followingproblems. To switch the direction of document transport, the ADF usuallyincludes a generally U-shaped turn-over path having an extremely smallradius of curvature. Therefore, the turn-over path cannot deal with arelatively thick document or a relatively long document. Specifically,when a document is conveyed along the turn-over path, an extremely greatconveying force is necessary (usually, the conveying force issubstantially proportional to the width of a document and proportionalto the square of the thickness of a document). Therefore, the turn-overpath does not allow rollers to convey a broad and thick documenttherethrough alone. Further, a long document is apt to bring about aloop jam when conveyed through the turn-over path. It follows that thekind of documents which can be dealt with by the above ADF is limited.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an imageforming apparatus having two reading sections, a document conveying unitand a fixing unit efficiently laid out therein in order to reduce spacesto be allocated thereto, and a document reading device capable ofconveying even a relatively thick document or a relatively long documentto a reading position defined in a turn-over type sheet-through ADF.

In accordance with the present invention, an image forming apparatusincludes a document conveying unit for conveying a document stacked on astacking section thereof, and a fixing unit for fixing a toner imageformed on a sheet, a reading section for reading an image of thedocument. A scanner support is constructed integrally with the fixingunit and supported by the body of the apparatus. A transport path iscommunicated to the document conveying unit and formed between a lowerguide surface provided on the top of the scanner support and an upperguide surface provided on the bottom of the document conveying unit. Afirst reading section is mounted on the document conveying unit and hasstationary optics facing the transport path; the stationary optics readsthe front of the document being conveyed along the transport path. Asecond reading section is mounted on the scanner support and hasstationary optics facing the transport path; the stationary optics readsthe rear of the document being conveyed along the transport path. Ifdesired, the reading optics of the first reading section and that of thesecond reading section may respectively read the rear and the front ofthe document.

Also, in accordance with the present invention, a document readingdevice includes a turn-over type sheet-through ADF including a documentseparating and feeding section for feeding a document while separatingit from the other documents, a generally U-shaped turn-over path forturning over the document, and a transport path along which the documentturned over by the turn-over path is conveyed. The transport pathincludes a reading position assigned to stationary optics. A manual feedunit forms an insertion path directly merging into the upstream side ofthe transport path following the turn-over path from the outside of thedevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptiontaken with the accompanying drawings in which:

FIG. 1 is a fragmentary view showing an image forming apparatusembodying the present invention;

FIG. 2 is an external perspective view showing a reading sectionincluded in the embodiment specifically;

FIG. 3 shows a specific configuration of a pressing mechanism alsoincluded in the embodiment and located at a reading position on an upperor a lower guide surface;

FIGS. 4A and 4B show a document reading device also embodying thepresent invention;

FIG. 5 is an exploded perspective view showing a mechanism included inthe device of FIGS. 4A and 4B for mounting and dismounting a manual feedunit;

FIG. 6 is an external perspective view of a document sensor included inthe device of FIGS. 4A and 4B;

FIG. 7 shows a specific arrangement of a plurality of document sensorsapplicable to the device of FIGS. 4A and 4B;

FIG. 8 is a view for describing the inclination of a manual feed unitalso included in the device of FIGS. 4A and 4B; and

FIG. 9 is a graph showing a relation between the inclination of themanual feed unit and the frictional load.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawings, an image forming apparatusembodying the present invention is shown and includes a body 1 forforming a toner image on a sheet by a conventional electrophotographicprocess. A fixing unit 2 fixes the toner image formed on the sheet 1. Ascanner support 3 is connected to the apparatus body 1 by a shaft 1 a.The scanner support 3 is rotatable about the shaft 1 a between anoperative or closed position contacting the apparatus body 1 a and aninoperative or open position uncovering the inside of the apparatus body1. A stay 3 a protrudes from the scanner support 3 into the apparatusbody 1 and carries the fixing unit 2 thereon. When the scanner support 3is held in its closed position, as shown in FIG. 1, the fixing unit 2 islocated in its preselected position for fixing the toner image on thesheet.

An ADF or automatic document conveying unit 4 is connected to thescanner support 3 by a shaft 3 b in such a manner as to be rotatablebetween an operative position shown in FIG. 1 an inoperative or openposition. A turn-over path 4 a is formed in the ADF unit 4 while aplurality of conveyor roller pairs 4 b are arranged along the turn-overpath 4 a. An upper guide surface 4 c forms the bottom of the ADF unit 4.A plurality of conveyor rollers 4 d are arranged along the upper guidesurface 4 c. A first and a second reading section 5 and 6 are mounted onthe ADF unit 4 and scanner support 3, respectively. The reading sections5 and 6 each includes a glass platen 7, a light source 8 forilluminating a document D, and a contact image sensor 9 for reading areflection from the document D with 1:1 optics.

A lower guide surface 3 c is provided on the top of the scanner support3. When the ADF unit 4 is held in the operative position shown in FIG.1, the lower guide surface 3 c cooperates with the upper guide surface 4c to form a transport path 4 a contiguous with the turn-over path 10. Aplurality of conveyor rollers 3 d are arranged along the lower guidesurface 3 c and contact, in the above condition, the conveyor rollers 4d, constituting roller pairs.

The first reading section 5 is mounted on the ADF unit 4 such that thebottom or contact surface of its glass platen 7 is flush with the upperguide surface 4 c. The contact image sensor 9 and light source 8 facethe transport path 10 via the glass platen 7. Likewise, the secondreading section 6 is mounted on the scanner support 3 such that the topor contact surface of its glass platen 7 is flush with the lower guidesurface 3 c; the contact image sensor 9 and light source 8 face the path10 via the glass platen 7.

The document D is laid on a tray or document stacking section 11 facedown. A pick-up roller 4 e, a conveyor roller 4 f and a reverse roller 4g feed the document to the turn-over path 4 a in cooperation. Theconveyor roller pairs 4 b convey the document D along the turn-over path4 a. The document D transferred from the turn-over path 4 a to thetransport path 10 is conveyed by the conveyor rollers 3 d and 4 d. Whilethe document D is conveyed at a preselected reading speed, the firstreading section 5 causes the light source 8 to illuminate the front ofthe document D and causes the image sensor 8 to receive the resultingreflection from the document D. In response, the image sensor orstationary optics 9 transforms the incident reflection to acorresponding electric scan signal. Assume that the document D istwo-sided, i.e., carries images on both sides thereof, and that theapparatus is so set as to read both sides of the document D beforehand.Then, the second reading section 6 causes its light source 8 toilluminate the other side or rear of the document D being conveyed atthe preselected speed. The image sensor 9 of the second reading section6 transforms the resulting reflection from the rear of the document D toa corresponding electric scan signal. The document D moved away from thereading sections 5 and 6 is driven out to another tray 12 by theconveyor rollers 3 d and 4 d.

When only the front of the document D is read, the scan signal is outputtime-serially from the contact image sensor 9 of the reading section 5.When both sides of the document D are read, the scan signals arerespectively output time-serially from the image sensors 9 of the tworeading sections 5 and 6. A controller, not shown, converts such a scansignal to an image signal. The apparatus body 1 forms an image on asheet on the basis of, e.g., the image signal and control signalsreceived from the controller.

In the illustrative embodiment, the document D is laid on the tray 11face down, i.e., with its front facing downward. Alternatively, thedocument D may, of course, be laid on the tray 11 face up, i.e., withits front facing upward. In such a case, the first and second readingsections 5 and 6 will respectively read the rear and the front of thedocument D with their image sensors 9.

FIG. 2 shows a specific configuration of one of the two reading sections5 and 6. FIG. 3 shows a specific configuration of a pressing mechanismlocated at each of the two reading positions defined on the upper andlower guide surfaces. As shown in FIG. 2, the glass platen 7. isimplemented as a single molding having stepped portions 7 a at bothsides thereof with respect to the widthwise direction of the document D(arrow A). Each stepped portion 7 a has a height δ, as measured from acontact surface 7 b, and is elongate in the document transport direction(arrow D) at the respective side of the glass platen 7. As shown in FIG.3, a pressing mechanism 20 is provided on the upper guide surface 3 c orlower guide surface 4 c such that it faces the reading section 5 or 6.The pressing mechanism 20 has a presser plate 22 and compression springs23 received in a recess 21 formed in the guide surface 3 c or 4 c.

The springs 23 constantly bias the presser plate 23 in the directionindicated by an arrow C in FIG. 3, so that the presser plate 22 usuallyremains in pressing contact with the upper surfaces of the steppedportions 7 a. In this condition, a passage 24 having the height δ isavailable between the contact surface 7 b and the presser plate 22 forthe document D to be passed while being read by the reading section 5 or6. The stepped portions 7 a molded integrally with the glass platen 7and forming the passage 24 is advantageous over spacer members, notshown, identical in configuration with the stepped portions 7 a, butadhered to the glass platen 7 for the following reason. The spacermembers would aggravate irregularity in the height δ of the passage 24due to the dimensional errors of the spacer members and irregularity inthe thickness of adhesive layers between the spacer members and theglass platen 7. Therefore, the stepped portions 7 a of the glass platen7 reduce the fluctuation in the length of the optical path between thecontact image sensor 9 and the front or the rear of the document D to beread. This allows the image sensor 9 to read the document D without anyblurring.

As stated above, the first reading section 5 is mounted on the ADF unit4 in order to promote the efficient use of the space available in theADF unit 4. Because the scanner support 3 supports the fixing unit 2within the apparatus body 1, the space available in the apparatus body 1is also efficiently used. These in combination reduce the overalldimensions of the apparatus, e.g., facsimile apparatus including the tworeading sections 5 and 6, ADF unit 4, and fixing unit 2.

Referring to FIG. 4A and 4B, a document reading device also embodyingthe present invention will be described. As shown, the document readingdevice is applied to a facsimile apparatus and generally made up of ascanner unit 31 and an ADF unit 33. The scanner unit 31 is mounted onthe scanner unit 31 via a shaft 32 and is openable about the shaft 32,as needed. The ADF unit 33 cooperates with the top of the scanner unit31 to constitute a turn-over type sheet-through ADF 34. The ADF 34includes a tray 35 to be loaded with a stack of documents, not shown. Apick-up roller 36, a conveyor roller 37 and a reverse roller 38constitute a sheet separating and feeding section 39. The conveyorroller 37 and reverse roller 38 are provided in a pair. The abovesection 39 separates the uppermost document from the underlyingdocuments on the tray 35, and feeds it from the tray 35. A generallyU-shaped turn-over path 41 includes a pair of conveyor rollers 40. Theturn-over path 41 merges into a substantially horizontal lineartransport path 45 including conveyor roller pairs 42 and 43 and adischarge roller pair 44. In this manner, the transport path 45 isformed between the surfaces of the scanner unit 31 and ADF unit 33facing each other. When the ADF unit 33 is opened, it uncovers thetransport path 45, as shown in FIG. 4B. A reading section 46 is mountedon the scanner unit 31 and has a contact image sensor, not shown, facingthe transport path 45 between the conveyor rollers 42 and 43. Thereading section 46 includes a glass platen 47. The contact image sensorplays the role of a so-called sheet scanner; the position where theimage sensor is located is the reading position.

A reading section 48 is mounted on the ADF unit 33 downstream of theabove reading section 46 in the direction of document transport. Thereading section 48 is an auxiliary reading section or a reading sectionfor reading the rear of a document, and also includes a contact imagesensor. Sensing means for sensing the size of the sheet to be fed fromthe tray 35 is built in the ADF unit 33.

A manual feed unit 49 is mounted on the ADF unit 33 in the vicinity ofthe shaft 32. The manual feed unit 49 forms an insertion path 50linearly merging into the transport path 45 at the upstream side of thepath 45. As shown in FIG. 5, bosses 51 (only one is shown) are formed onboth sides of the ADF unit 33. The manual feed unit 49 is rotatableabout the bosses 51 by about 90 degrees between a closed position and anopen position thereof. The manual feed unit 49 is formed with engagingportions 52 (only one is shown) respectively engaged with the bosses 51.Each engaging portion has its open portion so restricted as to beprevented from easily slipping out of the boss 51, but removable fromthe boss 51.

A document sensor 53 is mounted on the scanner unit 31 and disposed inthe insertion path 50. As shown in FIG. 6 specifically, the documentsensor 53 has an actuator 54 to be moved by a document inserted by hand,and is turned on and turned off thereby. In the illustrative embodiment,as shown in FIG. 7, the document sensor 53 is implemented as threedocument sensors 53 a, 53 b and 53 c each being responsive to aparticular document or sheet size in the widthwise directionperpendicular to the direction of document transport. In the specificarrangement shown in FIG. 7, the document sensor 53 a is located at thecenter in the widthwise direction. The document sensor 53 b is locatedoutside of the width of size A4, but inside of the width of size B4. Thedocument sensor 53 c is located outside of the width of size B4, butinside of size A3. When a document is inserted into the manual feed unit49 with its center used as a reference, the document sensor 53 a sensesit. If only the sensor 53 a is turned on, the document is determined tobe of size A4. When the sensors 53 a and 53 b are turned on, thedocument is determined to be of size B4. Further, when all the sensors53 a-53 c are turned on, the document is determined to be of size A3.

Usually, the manual feed unit 49 is held in its closed position orraised position, as indicated by a phantom line in FIG. 4A. Whendocuments of usual thickness and size are to be read by the facsimileapparatus, they are stacked on the tray 35 face up. When the readingoperation begins, the document separating and feeding section 39sequentially feeds the document into the turn-over path 41, theuppermost document first. The document fed by the above section 39 isdriven into the transport path 45 via the conveyor roller pair 42, whilebeing turned over by the turn-over path 41. While the conveyor rollerpair 42 and the following conveyor roller pair 43 d rive the documentstably at a preselected speed, the contact image sensor of the readingsection 46 sequentially reads the image of the document, one line at atime. The resulting image information is suitably processed byconventional means and then sent to a remote station. At the same time,information representative of the document size is also generated andsent to the remote station, so that the remote station can receive theimage data with an adequate size. The discharge roller pair 44 drivesthe document read by the image sensor to the outside. Such a procedureis repeated with the consecutive documents.

On the other hand, a document which is 0.4 mm thick or above or 1,200 mmlong or above cannot be automatically fed from the tray 35 because theturn-over path 41 is not suitable for such a kind of document. In thiscase, the manual feed unit 49 is opened or lowered away from the ADFunit 33, as indicated by a solid line in FIG. 4A. As a result, theinsertion path 50 is uncovered. The document is held by hand face downand then inserted into the insertion path 50 via the manual feed unit 49until its leading edge has been gripped by the conveyor roller pair 42.When the document sensor 53 a senses the leading edge of the document,the conveyor roller 42 as well as other constituents is renderedoperable. The size of the document (width) is determined on the basis ofthe outputs of the document sensors 53 a-53 c (ON or OFF), so that theremote station can receive image data with an adequate size. After theroller pair 42 has gripped the document and started driving it in thetransport path 45, it is sequentially read line by line by the contactimage sensor of the reading section 46. Subsequently, the document isdriven out by the discharge roller pair 44. This is also true with otherdocuments, if any. In this manner, even a relatively thick or arelatively long document can be fed linearly via the manual feed unit 49and insertion path 50 without being routed through a curved path.Therefore, the reading section 46 is capable of reading any desired kindof document.

Hereinafter will be discussed the inclination of the insertion path 50formed by the manual feed unit 49. When a relatively thick document, forexample, is inserted into the insertion path 45 via the manual feed unit49, it is preferable that the path extending from the unit 49 mergeslinearly into the transport path 45. However, such a path may beslightly inclined, as follows. Assume that the path formed by the manualfeed unit 49 is inclined by an angle 6, as shown in FIG. 8. As the angleθ increases, the frictional load ascribable to the document abuttingagainst the inlet portion 55 of the insertion path 50 increases, asshown in FIG. 9 specifically. Should the frictional load be excessive,it would cause, e.g., the conveyor roller 42 to slip during conveyanceand would result in various troubles. The troubles include the extensionof an image when the document is read by the image sensor, and thefailure of synchronization of a motor for driving the rollers.Therefore, the angle θ should preferably be confined in a range in whichthe frictional load is light, e.g., 15 degrees or less.

While the above embodiment has concentrated on a contact image sensor,it is similarly practicable with optics of the type having a lightsource, a reduction type focusing system, and a CCD (Charge CoupledDevice) image sensor. Further, in the embodiment, the apparatus body isimplemented as the ADF unit 33, and the manual feed unit 49 is removablyand openably mounted to the unit ADF unit 33. If desired, the scannerunit 31 may be constructed as an apparatus body and provided with themanual feed unit 49 thereon in the removable and openable configuration.

In summary, it will be seen that the present invention has variousunprecedented advantages as enumerated below.

(1) A space available in an ADF unit and a space available in anapparatus body are efficiently usable. Therefore, an image formingapparatus including two reading sections capable of reading both sidesof a document, a document transport unit and a fixing unit can have itsoverall dimensions reduced.

(2) When the ADF unit is opened away from its operative position, anupper guide surface and a lower guide surface are uncovered. In thiscondition, the operator can remove a document jamming a transport patheasily or clean or otherwise maintain, e.g., glass platens included inthe two reading sections.

(3) Stepped portions are molded integrally with the glass platen of eachreading section at opposite sides of the glass platen. The steppedportions form a passage for a document by contacting the upper guidesurface or the lower guide surface. Such stepped portions areadvantageous over spacer members identical in configuration with thestepped portions, but adhered to the glass platen. The spacer memberswould aggravate irregularity in the height of the passage due to thedimensional errors of the spacer members and irregularity in thethickness of adhesive layers between the spacer members and the glassplaten. Therefore, the stepped portions reduce fluctuation in the lengthof the optical path between stationary reading optics and the surface ofthe document to be read. This allows the stationary reading optics toread the document without any blurring.

(4) A turn-over type sheet-through ADF has thereinside a turn-over pathand a transport path contiguous with the turn-over path. A manual feedunit has an insertion path directly merging into the upstream end of thetransport path of the ADF from the outside. It follows that relativelythick or long documents not suitable for the turn-over path can bedirectly inserted into the transport path via the insertion path one byone. This allows the optics to read any kind of document.

(5) Because the manual feed unit is removably mounted to the apparatusbody, it can be held in its closed position when not used. This savesthe space to be occupied by the ADF. In addition, the manual feed unitcan be implemented as an optional unit for users not needing the manualfeeding function.

(6) Document sensors are provided for determining whether or not adocument is present on the insertion path, and the size of a documentpresent on the insertion path. This allows the operation for reading amanually inserted document to start at an adequate timing. In addition,the document size sensed beforehand allows, when the present inventionis applied to a facsimile apparatus, a receiving facsimile station toreceive image data with an adequate size.

(7) The insertion path merges into the transport path linearly at anangle capable of obviating an excessive frictional load. Therefore, whenthe reading section reads the document fed by hand, there can beeliminated the extension of an image ascribable to the slippage ofrollers and the failure of synchronization of a drive motor.

Various modifications will become possible for those skilled in the artafter receiving the teachings of the present disclosure withoutdeparting from the scope thereof.

What is claimed is:
 1. A document reading device comprising: a turn-overtype sheet-through ADF including a document separating and feedingsection for feeding a document while separating said document from otherdocuments, a generally U-shaped turn-over path for turning over thedocument, and a transport path along which said document turned over bysaid turn-over path is conveyed, said transport path including a readingposition assigned to stationary optics; and a manual feed unit formingan insertion path directly merging into an upstream side of saidtransport path following said turn-over path from outside of saiddevice, wherein when the manual feed unit is in an open position, themanual feed unit forms an inclined angle with respect to transport pathsuch that the insertion path merges into the transport path linearly atan inclined angle.
 2. A device as claimed in claim 1, wherein saidmanual feed unit is openably and removably mounted to an apparatus body.3. A device as claimed in claim 1, further comprising a document sensorfor determining whether or not the document is present in said insertionpath, and a size of the document.
 4. A device as claimed in claim 1,wherein said reading position includes a first reading position assignedto stationary optics for reading a first surface of the conveyeddocument and a second reading position assigned to stationary optics forreading a second surface of the conveyed document, said second surfacebeing opposite to said first surface.
 5. A device as claimed in claim 4,wherein said first surface is a front surface of said document and saidsecond surface is a rear surface of said document.
 6. A device asclaimed in claim 4, wherein said first surface is a rear surface of saiddocument and said second surface is a front surface of said document. 7.A document reading device comprising: a turn-over type sheet-through ADFincluding a document separating and feeding section for feeding adocument while separating said document from other documents, agenerally U-shaped turn-over path for turning over the document, and atransport path along which said document turned over by said turn-overpath is conveyed, said transport path including a reading positionassigned to stationary optics; and a manual feed unit forming aninsertion path directly merging into an upstream side of said transportpath following said turn-over path from outside of said device, whereinsaid insertion path merges into said transport path linearly at aninclined angle at which a frictional load is light, and wherein saidmanual feed unit is openably and removably mounted to an apparatus body.8. A device as claimed in claim 7, further comprising a document sensorfor determining whether or not the document is present in the insertionpath, and a size of the document.
 9. A device as claimed in claim 7,wherein said reading position includes a first reading position assignedto stationary optics for reading a first surface of the conveyeddocument and a second reading position assigned to stationary optics forreading a second surface of the conveyed document, said second surfacebeing opposite to said first surface.
 10. A device as claimed in claim9, wherein said first surface is a front surface of said document andsaid second surface is a rear surface of said document.
 11. A device asclaimed in claim 9, wherein said first surface is a rear surface of saiddocument and said second surface is a front surface of said document.